I have an 8830 through Verizon and thought I'd post the following information regarding my search for a Bluetooth headset.

I bought a Motorola HS850 through Buy.com (so yes, it was authentic) for my older Blackberry. Both on my old model and my new 8830, the HS850 never had enough volume for me to be able to hear other people while in the car. So, I did a lot of reading online and on this forum and decided to try the Jabra JX10 and the Plantronics Voyager 510. To give you an idea of what I did, I called my voicemail at work and listened to the greeting to get an idea of incoming volume, and also left myself messages and listened to them on my landline to get an idea of how clear the voice was with each. I did this exercise from inside my house, standing outside the front of my house, driving down the road with the windows up, and driving down the road with the windows down. Finally, I talked with my wife on each headset. Here's the results:

Motorola HS850: definite last place of the three. I can hardly hear on this in a quiet environment, and can't hear anything while in the car. Also had the most background noise and lowest outgoing volume of the three. Also, this thing is big and flops around on the ear a lot. Very annoying, and sorry I bought it.

Jabra JX10: I wanted to like this one a lot. The charging solutions it comes with (USB, cool desk cradle, and nice car charger) are outstanding. I liked the size, and I found the buttons easy to work with. It was also fairly comfortable. Incoming sound was definitely louder than the HS850, and outgoing sound was definitely clearer, louder, and had less background noise than the HS850. However, outgoing sound definitely has a "tin can" noise to it, to the point where I found some of my voicemails hard to understand and my wife asked me to stop talking on it after 30 seconds of conversation.

Plantronics 510: I put this on, made a call, and was amazed at how much louder the incoming volume was on this vs. the other two. The Jabra was much better than the Motorola, but the Plantronics was head and shoulders above the Jabra. The outgoing clarity was also much better than the Motorola. Compared to the Jabra, the outgoing voice has slightly less background noise than the Jabra, and is slightly louder as well. The biggest factor was the the outgoing voice on this does not have the "tin can" sound that can make the Jabra's outgoing voice hard to understand. This headset, while larger than the Jabra, was also much more comfortable due to the thicker ear hook and overall design. I did not like the charging solution this comes with (just one standard AC charger), but I can get a car charger on E-bay for $10 or less. I wish this was a little smaller not because the size is bothersome while wearing, but because it's not as discrete as the Jabra. However, the better comfort, louder incoming volume, and clearer and louder outgoing voice on this made this the clear winner. This one is also about $30 - $40 less than the Jabra.

In summary, I hate the Motorola. I really really wanted to like the Jabra best, but the Plantronics was definitely more comfortable and better at what a headset is suppossed to do: make clear, understandable communication between you and the person on the other end of the line.

Again, this was only using the 8830 from Verizon. Other devices may perform differently with each of these headsets. Hope this helps some of you out there.